The present invention relates to an image information transcoding apparatus, a bitstream transcoder and a method for transcoding and transmitting image information, in which processing such as change of resolution is carried out upon a compressed video signal so as to compress the video signal again, and the compressed video signal is output.
For example, the background art related to the present invention includes a technique disclosed in JP-A-2001-285875. The technique disclosed in this official gazette has an object that is “to reduce computational cost and video memory capacity required for transcoding MPEG (Moving Pictures Expert Group)-2 (ISO/IEC 13818) image compressed information to MPEG-4 (ISO/IEC 14496) image compressed information”. An image information transcoding apparatus according to the invention disclosed in this official gazette “includes an MPEG-2 image information decoding portion 18 which uses only 4×8 components out of 8×8 components of DCT coefficients of a macroblock to decode an interlaced image; a scanning conversion portion 19 which selects one of first and second fields of the interlaced image decoded by the MPEG-2 image information decoding portion 18, and generates an image by sequential scanning; a down sampler 20 which performs horizontal sampling on the image generated by the scanning conversion portion 19; a down sampler 21 which performs vertical down sampling on the image down-sampled by the down-sampler 20; and encoding means 22 which encodes the image down-sampled by the down sampler 21 so as to obtain MPEG-4 image compressed information”.